1. Field of the Invention
The present invention relates to an image forming process for forming a protective layer of a thermoplastic resin film on a recording medium and an image forming apparatus for carrying out this process.
2. Related Background Art
In recent years, the technique of ink-jet recording has made noteworthy progress and the resultant image quality has reached a level equal or superior to that of a silver halide print. A known recording media used for this ink-jet recording process includes an image-receiving layer on a base material such as paper. This layer contains porous particles excellent at absorbing and fixing recording liquid.
Also utilized is a laminating treatment of a recorded image which provides waterproof characteristics, light resistance and glossiness. This treatment is achieved by transferring and laminating a transfer layer, comprised of a layer of thermoplastic resin on a base material, onto a recorded image by heat and pressure adhesion. By having a UV absorbing agent contained in the transfer layer during this treatment, it is also possible to provide a print with sufficient light resistance.
Furthermore, many resin-using laminating treatments of an image have been established for easily providing wear resistance, solvent resistance, or the like, by devising the material and construction of this transfer layer.
FIGS. 3A to 3C are schematic sectional views of a conventional laminating method. The film with a base material shown in FIG. 3A basically comprises a transfer layer 101 to be transferred and laminated onto the surface of a recorded image and a base material film 102 for bearing the transfer layer 101. The transfer layer 101 can be peeled off from the base material film 102 so as to be transferred and laminated onto the image-receiving layer of a recording medium after recording.
As shown in FIG. 3B, the transfer layer 101 is laminated while remaining borne on the base material film 102. The transfer layer 101 directly covers the top of the image-receiving layer 103a on an ink-jet image-receiving paper 103 after recording and is then applied onto the image-receiving layer 103a by pressurization and/or fusion.
As shown in FIG. 3C, the base material film 102 is peeled off from the transfer layer 101 after the transfer layer is applied onto the recorded image, and the transfer layer 101 alone is left as a protective layer on the image-receiving layer 103a. 
The principal problem of the construction comprising a transfer layer 101 and a base material film 102, as shown in FIGS. 3A, 3B and 3C, is high cost. In a laminating treatment as discussed above, the base material film 102 must be comprised of a heat resistant material on which a resin layer to be transferred by heat and pressure adhesion on the recording side is formed by coating. In addition, this base material film 102 must exhibit flatness sufficient for giving the gloss of a protective film after the transfer. The cost of this base material film 102 is higher than that of either a transfer material which remains as a final product or a coating of a transfer layer. Some sufficiently stable and deformation-free raw materials for a protective layer, with conditions assumed for thermal transfer, and in which preannealing controls thermal shrinkage, include PET film, polyamide film, and polyimide film. Each of these materials is of high-cost and thus a wide variety of low-cost, general purpose applications are difficult to create.
The second problem of this construction is that the base material film 102 becomes waste once used. To minimize processing costs, coating of the transfer layer 101 is ordinarily executed on a wide roll before slitting. Thus, recycling of used base material film 102 cannot be directly performed. If used base material film 102 was recycled, it would be done on the raw material level. Thus, there would be labor costs for collecting and recycling them in addition to expenses including a mechanism for rewinding a film after the image transfer in an apparatus, a space for housing the mechanism, and a power source or control system for moving the mechanism. If a laminate material has been cut, winding is unnecessary, but a mechanism for carrying used base material film 102 and accumulating it in a predetermined space is still necessary.
The third problem of this construction is that the function of a protective layer transferred and formed varies according to factors including physical properties, surface properties, and thickness. These especially affect the glossiness, the adhesion of a film and the bubble releasability. The transfer process of a glossy protective layer is a complicated process to which many parameters contribute, and the addition of such influential variable factors is unfavorable.